BUENOS AIRES (Reuters) - The lower house of Argentina's Congress on Thursday narrowly passed a bill to legalize abortion through 14 weeks of pregnancy after a tight vote on a proposal that has divided the South American nation.

The bill, which will now go to the Senate, would include abortion in the free public health system. It passed the house with 129 votes in favour and 125 against after an all-night debate.

"We are dealing with a public health issue that cannot be addressed with blinders, nor with morals and ethics and much less religion," opposition congresswoman Mayra Mendoza, one of the driving forces of the proposal, said in a speech. "This is also a matter of social justice."

The opposition, as well as allies of President Mauricio Macri, were divided on the issue. Macri has encouraged his party members to vote as they see fit even though he is personally opposed to the proposal.

Argentina, like most countries in Latin America, currently permits abortion in specific cases, including rape and risk to the mother's life. Rights groups have criticized a requirement for a judge's permission, which often results in lengthy delays or denial of the procedure.